fix : Resolved an issue where the time range was not normally represe…

…nted in the time grid when the difference between the main time zone offset and the secondary time zone offset was less than 1 hour (fix #488)

src/js/view/week/timeGrid.js

@@ -43,8 +43,9 @@ function getHoursLabels(opt, hasHourMarker, timezoneOffset, styles) {
     var hoursRange = util.range(0, 24);
     var nowAroundHours = null;
     var nowHours, nowHoursIndex;
+    var isNegativeZero = 1 / -Infinity === shiftByOffset;
 
-    if (shiftByOffset < 0 && shiftMinutes > 0) {
+    if ((shiftByOffset < 0 || isNegativeZero) && shiftMinutes > 0) {
         shiftByOffset -= 1;
     }